Nanoscale devices using switching materials such as metal oxides that exhibit resistive switching behavior have recently been reported. The switching behavior of such devices has been linked to the memristor circuit element theory originally predicted in 1971 by L. O. Chua. The discovery of the memristive behavior in the nanoscale switching devices has generated significant interest, and there are substantial on-going research efforts to further develop such nanoscale switches and to implement them in various applications. One of the many important potential applications is to use such switching devices as memory units to store digital data. A memory array may be constructed with such switching devices in a crossbar configuration to provide a very high device density. For memory applications, it is desirable to have nanoscale switching devices with good operation endurance so that they can go through many switching cycles without failure.